New search for global warming at poles

For the next two years, the coldest places on Earth will become some of the hottest laboratories in the history of modern science.

This Thursday marks the official start of the International Polar Year (IPY), an unprecedented research assault on Antarctica and the Arctic.

Some 10,000 scientists from more than 60 countries launched the push because of significant changes they see taking place at these frozen ends of the Earth. Many hold that global warming is triggering these changes, including shrinking sea ice in the Arctic Ocean, thawing permafrost, and growing instability in Greenland's ice cap and in some floes coursing through Antarctica's ice cap.

The goal is to gain a deeper understanding of processes affecting everything from the flow of glaciers, and key features of polar climate to plankton and polar bears. In addition, researchers plan to leave a legacy of networked, standard sensors and buoys that will help track changes in these crucial regions long after the IPY ends.

Why North and South poles matter

At first glance, the poles may seem too remote to matter to anyone who doesn't live there. But Earth's "cryosphere" – its high-latitude regions of snow and ice – represents a central piece of the climate system. The poles act as sinks for the heat generated in the tropics and carried toward higher latitudes by the oceans and atmosphere. Over many centuries, the ice caps on Greenland and Antarctica hold the key to future sea-level rise as the climate warms up north.

Thus, the hidden hand of a changing Arctic reaches farther south than icebergs alone suggest.

"There is no magic curtain that drops down at 60 degrees north," says ice scientist Jacqueline Richter-Menge, who heads climate-related research at the US Army Corps of Engineers' Cold Regions Research and Engineering Laboratory in Hanover, N.H.

Changes in ecosystems

For instance, ecosystems stretching from the Labrador Sea to the continental shelf off North Carolina are changing because colder, less-salty water is flowing along the continental shelf from the Arctic Ocean into the northwest Atlantic, according to two Cornell University scientists. Many researchers attribute the Arctic Ocean's freshening to global warming.

The scientists note that while overfishing triggered the collapse of lucrative cod fishing off the Canadian Maritime Provinces, this fresher, colder water along the shelf has hindered the cod's recovery there compared with stocks farther south.

In their place, marine life, including shrimp and snow crab, that cod would have eaten are flourishing. The changes in water conditions have altered the timing for peak production among tiny plankton that nourish creatures higher up the food chain.

"These timing changes are going to lead to changes in the ecosystem. There will be winners and losers in the ecosystem. And there will be winners and losers in society," says Charles Greene, a Cornell oceanographer who was a co-author of the report.

Meanwhile, in the south, scientists working on the global Census of Marine Life say they see biologically significant shifts in marine life along the sea floor that once anchored two large ice shelves known as Larson A and B. They broke away from the Antarctic Peninsula over the past 12 years.

"The more we understand what's going on, the more winners there will be," Dr. Greene says.

International grass-roots effort

The IPY coincides with the 50th anniversary of the International Geophysical Year (IGY), the first postwar effort to study the entire planet, from the deep-sea floor and below to the outermost reaches of the atmosphere. Although this year's effort is dubbed the polar year, it spans two years to allow scientists to track conditions at both poles through a complete summer-winter-summer cycle.

The IPY includes more biology and ecology to better gauge the effect changes are having on plants and animals, as well as on the organic carbon stored in frozen tundra. Scientists say that as the Arctic in particular warms, they expect this carbon to reach the atmosphere as carbon dioxide and methane – turning the Great White North into a source of heat-trapping greenhouse gases.

Unlike the IGY, "this is a very grass-roots effort," says Robin Bell, a senior scientist at the Lamont-Doherty Earth Observatory in Palisades, N.Y.

Last week, Dr. Bell and colleagues described how lakes in the right location beneath Antarctic ice "rivers" accelerate the ice's movement toward the sea.

The poles "are the parts of the planet changing most rapidly" with global warming, she says. Understanding them is key to understanding how the rest of the planet is likely to respond.